as·​tro·​labe ˈa-strə-ˌlāb How to pronounce astrolabe (audio)
 also  -ˌlab
: a compact instrument used to observe and calculate the position of celestial bodies before the invention of the sextant

Illustration of astrolabe

Illustration of astrolabe

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The Astrolabe and the Stars

"Thyn Astrolabie hath a ring to putten on the thombe of thi right hond in taking the height of thinges." Thus begins a description of the astrolabe in A Treatise on the Astrolabe, a medieval user's guide penned by an amateur astronomer by the name of Geoffrey Chaucer. Chaucer is best known for his Middle English poetic masterpiece The Canterbury Tales, but when his nose wasn't buried in his writing, Chaucer was stargazing, and some of his passion for the heavens rubbed off on his son Lewis, who had displayed a special "abilite to lerne sciences touching nombres and proporciouns." Chaucer dedicated his treatise to the 10-year-old boy, setting his instructions not in the usual Latin, but in "naked wordes in Englissh" so that little Lewis could understand. When he got older, Lewis may have learned that the word astrolabe traces to the Greek name for the instrument.

Examples of astrolabe in a Sentence

Recent Examples on the Web Another letter from Synesius addressed Hypatia’s work on her astrolabe, an apparatus that served as a model of the sky and could be used to answer astronomical questions. Emilie Le Beau Lucchesi, Discover Magazine, 7 June 2023 That included this metal disk, thought to be an astrolabe — an instrument that mariners used to navigate by measuring the height of celestial bodies above the horizon. Ernie Mastroianni, Discover Magazine, 25 June 2019 Likely constructed between 1496 and 1501, the astrolabe was certified this year as the oldest example known. Ernie Mastroianni, Discover Magazine, 25 June 2019 Allen has also purchased a collection owned by a former investor and a rare bronze Spanish navigational astrolabe found off Lucaya Beach that will be on display as well. Bill Springer, Forbes, 31 July 2022 There are also lots of smaller instruments—thermometers, sextants, astrolabes—and plenty of globes, as well as an enormous armillary sphere, designed and built by the Italian astronomer Antonio Santucci. Jennifer Ouellette, Ars Technica, 17 May 2020 John has a gift just for Bree, an astrolabe, that allows them to find their position in the universe and tell the time. Maureen Lee Lenker,, 13 Apr. 2020 But that’s because its function is more astrolabe than clock. Alex Schechter, National Geographic, 4 Nov. 2019 Some of the classes included: Social Studies/Math where students created astrolabes and used them outside to measure locations of buildings, trees, etc. and gauge distance and patterns. Sam Boyer, cleveland, 20 Sep. 2019 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'astrolabe.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Middle English astrelabie, astellabre, astyrlabe, borrowed from Anglo-French astrelabe, astrolabre (continental Middle French astrelabe, astrolabe), borrowed from Medieval Latin astrolabium, borrowed from Late Greek astrolábion, re-formation of Greek astrolábos "armillary sphere," from astro- astro- + -labos, derivative in nominal compounds from the aorist stem of lambánein "to take hold of, grasp" — more at latch entry 1

First Known Use

14th century, in the meaning defined above

Time Traveler
The first known use of astrolabe was in the 14th century


Dictionary Entries Near astrolabe

Cite this Entry

“Astrolabe.” Dictionary, Merriam-Webster, Accessed 4 Oct. 2023.

Kids Definition


as·​tro·​labe ˈas-trə-ˌlāb How to pronounce astrolabe (audio)
: an instrument for observing the positions of heavenly bodies that was used before the sextant was invented

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